Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Threats to Bard with this build
You want to start Krugs for the buff it provides. This will allow you to complete red without dying.
Use your q and meeps to kite red around to avoid dmg.
After red you may have to back which is perfectly fine. Go back and purchase hunters potion for more sustain.
Bard is mostly viable for his ability to gank and chain down enemies.
You want heavy burst champions on your team.
Bard's main goal is to collect chimes and to be anoying. If you can help lanes get ahead with cc you have succeded. Once you get devourer going tho, you will be two shotting squishies left and right.